Exercise # 13 (Characterization of Bacterial Cultures)

bacterial colony

consists of numerous bacterial cells derived from one parent. Colonies of different types of bacteria can be distinct in appearance

colony morphology

refers to the visible characteristics of a colony.

• Punctiform (or pin point)

<1 mm

• Small

1-2 mm

• Medium

3-4 mm

• Large

>5 mm

• Filiform

uniform growth along the line of inoculation

• Echinulate

margins of growth have a toothed appearance

• Beaded

separate or semiconfluent colonies

• Effuse

growth is thin, veil-like, unusually spreading

• Arborescent

branched, tree-like growth

• Rhizoid

root-like appearance

Pellicle

• Some float on top of the medium and produce a membrane at the surface called

Turbidity

• Some produce uniform growth and cloud the broth

• Ring type

dense growth around the surface

• Flocculent

made of floating adherent masses of bacteria

• Membranous

thin membrane-like growth covering the entire surface

• Pellicle

thick membrane-like growth covering the entire surface

• Turbid

the medium is cloudy

• Granular

the medium has small particles visible in suspension

• Flocculent

the medium has small masses visible in it

• Flaky

the medium has large particles visible in suspension